The true experimental tweak thread

[John769]

I suppose it would be as easy a mod to float the secondary as it was with the Airlink.   Definitely one to consider..cheers

 

Yes, I have been using his 100va, 12v Sigma clone LPS for a couple of years now. 

[Solid-State]

1 hour ago, Cornan said:

 

It was a different board. I have 16 LT3045 boards and 11 of them is currently used in my setup! ?

this was the first time I tried the Kemet’s on both input and output on series LT3045. I have only tried it at my router end before where I use a single LT3045.

 

As I have told you before the PowerWalker needs testing. It does’nt improve everywhere. It can make it worse in the wrong spot.

I do not think that cutting that cable will give you a much different result. Only minor. You are probably better off trying it somewhere else.

 

Here is a tip for a great AC mains plug kit https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F132303196697

 

You might also be interested in the sellers other items, like this balanced IT for example https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F132477069895

 

?

 

 

Yeah sure
1 set of OYAIDE fore 26 usd ,,,,,

FAKE,, don't buy

[Solid-State]

2 hours ago, Cornan said:

 

Boring right? Don’t let me bore you. Just keep on moving until you find your happy place! ???

did that a long time ago

[Cornan]

2 minutes ago, TubeMan said:

did that a long time ago

 

As written in you’re profile then. Done here! ?

[John769]

3 hours ago, Cornan said:

he sells great high quality products and the IT got a 5 star review.

is that one in his ebay feedback or elsewhere? 

 

These IT's are one of the biggest bang for bucks available in audio IMO.  I guess your future is still the 'all in one box' project? 

[Cornan]

14 minutes ago, John769 said:

is that one in his ebay feedback or elsewhere? 

 

These IT's are one of the biggest bang for bucks available in audio IMO.  I guess your future is still the 'all in one box' project? 

 

Just the feedback on eBay!

Their toroidal transformers seem to be good and the price is really great. If it will match up with ATL is impossible to know without a bit of gamble. My balanced isolated PS will have their toroidal transformers as well. If you wait I will let you know how they sound. At least it will give you an indication if their transformers sounds good.

Actually not! I have left the idea of a all in one solution after realizing how big and heavy it would need to be with so many toroidal transformers (one 50VA transformer for each voltage reg plus one 500VA toroidal transformer for all due to the balanced construction) in a single box plus the heat that would most certainly require fans. LT3045s do not like to be hot! ?

[John769]

15 minutes ago, Cornan said:

If you wait I will let you know how they sound

That would be really helpful, thanks man..!

[drjimwillie]

Hi - I just received a MGE (Topaz clone) Ultra Isolation Transformer 91097-31T it is 750 VA.

I live in the USA and want to use it 120V in - 120V out.  It came wired 120V in - 240V out.

I posted images and questions over on the AC mains isolation transformer thread.

I received some schematics and the most detailed wiring diagram, from the back of a transformer access door, that I have seen yet.

One of the CA senior contributors (an angel), helped me get it wired correctly, but I still have questions.

I have it wired: Primary (input)

120V Hot (black) ->H1

jumper H2 + H3

120V Neutral (white) -> H4

Ground from the wall ->G

 

Secondary (output)

Output 1 Hot (black)

jumper X2 + X3 & X3 + G

Output 2 Hot (white) ->X4

G-> output grounds

 

He also advised "wire in a green cable & join the Primary and Secondary terminals".  I did not do this because I ASSUMED that it is part of the factory wiring & because I got continuity from the input to the output ground.

 

My Angel feels strongly that the Secondary be grounded as you can see from above, and from all of his posts.  I would like the secondary to be floating because I understand that J.S. says it is safer that way, it looks like from the schematic it is designed that way & I understand that it sounds better.  Please correct me if I am wrong on any of these points, please.

 

Wired with the jumper X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 62.7V

X4 - G   = 62.7V

 

With the jumper removed from X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 32.3V (is this weird that these do not match)

X4 - G   = 86.0V (is this weird that these do not match)

 

I thought from the @JohnSwenson example that I would measure 0V from the ground because it is floating??

What is strange is that when I look at the access door schematic, that this transformer is wired 220V in - 220V out.

 

My questions are:

1. With the jumper removed from X3 + G is this a floating Secondary?

        a. Is it wired correctly for a floating secondary?

        b.  Do I want it wired for a floating secondary?

2.  Is this wired Balanced?

        a.  How do I wire it for balanced?

        b. Do I want it wired balanced?

I am so excited - thank you very much for your help! (then I did a little dance)  (any comments are appreciated)

Will

 

[Cornan]

3 hours ago, drjimwillie said:

Hi - I just received a MGE (Topaz clone) Ultra Isolation Transformer 91097-31T it is 750 VA.

I live in the USA and want to use it 120V in - 120V out.  It came wired 120V in - 240V out.

I posted images and questions over on the AC mains isolation transformer thread.

I received some schematics and the most detailed wiring diagram, from the back of a transformer access door, that I have seen yet.

One of the CA senior contributors (an angel), helped me get it wired correctly, but I still have questions.

I have it wired: Primary (input)

120V Hot (black) ->H1

jumper H2 + H3

120V Neutral (white) -> H4

Ground from the wall ->G

 

Secondary (output)

Output 1 Hot (black)

jumper X2 + X3 & X3 + G

Output 2 Hot (white) ->X4

G-> output grounds

 

He also advised "wire in a green cable & join the Primary and Secondary terminals".  I did not do this because I ASSUMED that it is part of the factory wiring & because I got continuity from the input to the output ground.

 

My Angel feels strongly that the Secondary be grounded as you can see from above, and from all of his posts.  I would like the secondary to be floating because I understand that J.S. says it is safer that way, it looks like from the schematic it is designed that way & I understand that it sounds better.  Please correct me if I am wrong on any of these points, please.

 

Wired with the jumper X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 62.7V

X4 - G   = 62.7V

 

With the jumper removed from X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 32.3V (is this weird that these do not match)

X4 - G   = 86.0V (is this weird that these do not match)

 

I thought from the @JohnSwenson example that I would measure 0V from the ground because it is floating??

What is strange is that when I look at the access door schematic, that this transformer is wired 220V in - 220V out.

 

My questions are:

1. With the jumper removed from X3 + G is this a floating Secondary?

        a. Is it wired correctly for a floating secondary?

        b.  Do I want it wired for a floating secondary?

2.  Is this wired Balanced?

        a.  How do I wire it for balanced?

        b. Do I want it wired balanced?

I am so excited - thank you very much for your help! (then I did a little dance)  (any comments are appreciated)

Will

 

 

Hi Will!

Yes, @One and a half is an angel! ? Sometimes a grumpy angel, but still an angel! ?

 

When John Swenson is talking about an isolation transformer with floating secondary he is talking about unbalanced isolation transformers. They are usually called safety isolation transformers because they are used for personal protection when people are repairing electronic devices.

Balanced wiring is a bit different. It is not something you would use to repair electronic devices since both neutral and hot could kill you in an instant. Imagine that you float the ground which is the only protection you’ve got if something goes wrong. You’ll need a 2-pole RCD/GFCI at the output of a balanced isolation transformer with floating secondary plus a star earthed power distributor to ensure that the 2-pole RCD/GFCI trips when something goes wrong in any of the connected devices.

 

How do you float a balanced isolation transformer then? I cannot help you with the actual wiring of a Topaz. I would hate to give you a wrong answer! I do not own a Topaz and are on 230VAC myself. I personally ordered mine ready made from someone who knows about these things. ATL Hi-Fi.

The center tap is connected to the chassis as well as the electromagnetic shielding and the IEC safety ground input. This is by far the best isolation transformer that I have tried when it comes to SQ. One and a half will disagree due to the personal safety issues involved plus that he is not a believer in the floating aspect of a balanced isolation transformer. @Abtr will probably agree and is the only one that might be able to help you with the wiring (That I know about here on CA). However, before entering that mod you’ve got to know about the risks and how to avoid them.

 

According to me= yes you want it balanced and if SQ is important to you and you are aware of the precautions then yes you want it floating as well. ?

[drjimwillie]

OK - so then I  probably do not want to wire it balanced. 

 How do I confirm that I have it wired unbalanced with the floating secondary, so that it is according to J.S. Safe?

 Can you help me with any of my other questions from above? 

 How is my transformer wired now? 

 Why do I get voltage from the hot and the neutral?

Why when the jumper is removed from X3 - G, do I get different voltages X1 or X4 to G. Is it an issue?

Thank you 

 

[Cornan]

50 minutes ago, drjimwillie said:

OK - so then I  probably do not want to wire it balanced. 

 How do I confirm that I have it wired unbalanced with the floating secondary, so that it is according to J.S. Safe?

 Can you help me with any of my other questions from above? 

 How is my transformer wired now? 

 Why do I get voltage from the hot and the neutral?

Why when the jumper is removed from X3 - G, do I get different voltages X1 or X4 to G. Is it an issue?

Thank you 

 

 

Yes, you probably want it balanced for audio! ? You just need to mind the 0v reference. Either you will install a dedicated circuit and make it grounded or float the secondary. 

 

It looks balanced to me in this configuration:

 

Wired with the jumper X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 62.7V

X4 - G   = 62.7V

 

With a balanced configuration you will expect roughly 60VAC on both neutral and hot. The voltage on the ground should be 60v as well when grounded. With a floating secondary I would expect a different figure, but not sure what figure that will be though since you are in fact grounding the center-tap (otherwise it will not be balanced) but the center-tap ground, the electromagnetic shield and the IEC safety ground must all be connected to the chassi, preferably at a star-earth point.

 

Not sure why you measure the jumpers voltage? The only thing that matters is the output voltage at the two output hot (black and white) and center tap ground (output grounds). I get very confused with your X1 to X4 figures I must say. Input seems good to me.

If you want it unbalanced you want to see 0v-120v on neutral and hot.

[drjimwillie]

I am not  measuring the jumpers. 

 If you look at my original post, I have two sets of measurements.  The one that you brought down to reference is where, I believe the secondary is grounded.  The jumpers go from  X2 + X3  then a jumper goes from X3 + G.  X1  has the black wire & X4  has the white wire.  So I am measuring from the output wires to ground.   And the reading is 62.7V on both. 

 

 When I remove the jumper from X3 + G,  I get an asymmetric reading when measuring the output wires to ground (32V & 86V) but I don't know if this matters because it is supposed to be floating from ground. 

 

 I don't know what is grounded to the chassis or the shields, I would have to take the whole thing apart I think to find out.  

 

 I bought a 20 amp GFI to use  because it appears this is balanced and I want the secondary floating. 

 

 I hope you don't mind that I came here to ask questions. It was suggested that I would not get the answers I wanted on the other thread  

[Cornan]

6 hours ago, drjimwillie said:

I am not  measuring the jumpers. 

 If you look at my original post, I have two sets of measurements.  The one that you brought down to reference is where, I believe the secondary is grounded.  The jumpers go from  X2 + X3  then a jumper goes from X3 + G.  X1  has the black wire & X4  has the white wire.  So I am measuring from the output wires to ground.   And the reading is 62.7V on both. 

 

 When I remove the jumper from X3 + G,  I get an asymmetric reading when measuring the output wires to ground (32V & 86V) but I don't know if this matters because it is supposed to be floating from ground. 

 

 I don't know what is grounded to the chassis or the shields, I would have to take the whole thing apart I think to find out.  

 

 I bought a 20 amp GFI to use  because it appears this is balanced and I want the secondary floating. 

 

 I hope you don't mind that I came here to ask questions. It was suggested that I would not get the answers I wanted on the other thread  

 

If you remove the jumpers between X3+G you probably do not have a balanced configuration anymore. There must be a wire from X3 (center tap) that is attached to a bolt to the chassi. You got to make sure that the input ground is attached to the chassi as well. Is there any connections to the electromagnetic shield? 

If you post pictures it is much easier to help you. I am not an E.E. and right now it feels like I am blindfolded trying to walk you through traffic! ?

 

A 20A GFCI won’t help you with a balanced IT. It is most likely a 1-pole one. It needs to be a 2-pole RCD/GFCI. Very important for personal safety.

 

You are welcome to post here. I will help you, but only with comfortable answers when it comes to AC configurations since a wrong advice could potensially kill you. ?

[drjimwillie]

 So if Center Of two coils and secondary are required for the transformer to be wired balanced, then by definition it is impossible to have the secondary floating? Is that correct? 

 Do I need the secondary to be floating if it is wired balanced? If so, why, please. 

 

 These are photos of the transformer before I rewired it.  (Except for the copper wire)

 Look at these screw down terminal blocks.   When I received it there were the ones teeny little aluminum jumpers.   I have to believe that these teeny wires are going to impede my power.  I put in the one copper wire you can see on the output.  There is some little loop in the way which makes it hard to put anything in  under the screw.  I ordered new terminal blocks, but now that I look at this picture I don't think I can make it work because the screw holes are too close together.  What do you think.  

 

 I can see a ground wire going to the frame on the input and the output.   There is a green wire going into the coils on the input.   There are two gray wires coming out from the interior on the output,  I am not sure what they do?

 

 

[Abtr]

22 hours ago, drjimwillie said:

Hi - I just received a MGE (Topaz clone) Ultra Isolation Transformer 91097-31T it is 750 VA.

I live in the USA and want to use it 120V in - 120V out.  It came wired 120V in - 240V out.

I posted images and questions over on the AC mains isolation transformer thread.

I received some schematics and the most detailed wiring diagram, from the back of a transformer access door, that I have seen yet.

One of the CA senior contributors (an angel), helped me get it wired correctly, but I still have questions.

I have it wired: Primary (input)

120V Hot (black) ->H1

jumper H2 + H3

120V Neutral (white) -> H4

Ground from the wall ->G

 

Secondary (output)

Output 1 Hot (black)

jumper X2 + X3 & X3 + G

Output 2 Hot (white) ->X4

G-> output grounds

 

He also advised "wire in a green cable & join the Primary and Secondary terminals".  I did not do this because I ASSUMED that it is part of the factory wiring & because I got continuity from the input to the output ground.

 

My Angel feels strongly that the Secondary be grounded as you can see from above, and from all of his posts.  I would like the secondary to be floating because I understand that J.S. says it is safer that way, it looks like from the schematic it is designed that way & I understand that it sounds better.  Please correct me if I am wrong on any of these points, please.

 

Wired with the jumper X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 62.7V

X4 - G   = 62.7V

 

With the jumper removed from X3 + G, I measure:

X1 - X2 = 62.7V

X4 - X2 = 62.7V

X1 - X4 = 126V

X1 - G   = 32.3V (is this weird that these do not match)

X4 - G   = 86.0V (is this weird that these do not match)

 

I thought from the @JohnSwenson example that I would measure 0V from the ground because it is floating??

What is strange is that when I look at the access door schematic, that this transformer is wired 220V in - 220V out.

 

My questions are:

1. With the jumper removed from X3 + G is this a floating Secondary?

        a. Is it wired correctly for a floating secondary?

        b.  Do I want it wired for a floating secondary?

2.  Is this wired Balanced?

        a.  How do I wire it for balanced?

        b. Do I want it wired balanced?

I am so excited - thank you very much for your help! (then I did a little dance)  (any comments are appreciated)

Will

 

 

Basically a low capacitance IT (like a Topaz or your MGE) with unbalanced secondary isolates/filters high frequency noise from the mains power. In addition a balanced secondary (largely) eliminates (common mode) noise thrown back into the mains by the load, which might otherwise end up as distortion in the analogue audio signal. Below are the possible balanced/unbalanced/floating/non-floating connection schemes for your IT as far as I can tell:

*Always* connect mains 120V hot (black) to H1, mains 120V neutral (white) to H4 and mains earth to  G at the input. Note that input G is (should be) internally connected to primary neutral (H4), the electrostatic shield and the chassis of the transformer.

For 120V ->120V unbalanced non-floating output, jump H1 (H1A) and H3, jump H2 and H4, jump X1 and X3, jump  X2 and X4, jump X4 and G and connect both the green-yellow wire and the solid green wire at the output to X4. This is safe because your gear's chassis is now connected to mains earth and a short to chassis will trip your central GFCI and/or blow a mains fuse.

For 120V -> 120V unbalanced *floating* output, disconnect the green-yellow wire and the solid green wire from G at the output. Note that this is *unsafe* because now your gear's chassis is not connected to mains earth and a short to chassis will not trip your central GFCI or blow a mains fuse!

For 120V -> 120V balanced non-floating output, jump H2 and H3 (and remove the jumpers between H1A and H3 and between H2 and H4), jump X2 and X3 and remove the jumper at the top between G and X4 at the output, connect both the green-yellow wire and the solid green wire to G at the output and jump G to X2/X3 (which is now the secondary center tap). This is safe because your gear's chassis is connected to mains earth and a short to chassis will trip your central GFCI and/or blow a mains fuse.

Now, for 120V -> 120V balanced *floating* output, connect everything as was described above for a 120V -> 120V balanced non-floating output, and simply disconnect the yellow-green earth wire from G at the output but keep the solid green wire connected to G. This is *unsafe* because your gear's chassis is not connected to mains earth and a short to chassis will therefore not trip your central GFCI or blow a mains fuse! However, you can make this safe by installing a 2 pole RCD/GFCI at the output of the IT. Your gear’s chassis is connected to the zero voltage center tap (X2/X3) of the balanced secondary and a short to chassis will trip the 2 pole GFCI at the output of the IT.

 

Note that you should experimentally determine whether in your case a floating secondary sounds better than a non-floating secondary. In theory if you have no DC offset in your AC mains power and ground, then a *non-floating* balanced secondary should be best for CM noise reduction/cancellation..

[drjimwillie]

@Abtr thank you so much for the extensive reply. 

 When you say wiring the transformer balanced eliminates common mode noise, is that because it does not get created in the first place or because it gets dumped into the ground,  or someplace else?  

 

 I just posted two pictures of my transformer.   At the input there is a green wire going into the chassis.  On the output there are two gray wires coming out of the chassis.   No green wire.   How do I deal with this, please. 

 

 If I plan to experiment with floating the secondary, balanced then I need to purchase and use the two pole GFI before I can experiment, correct? 

 

 I plan to hardwire an Alt hifi DC blocker before the IT.  So then  I will only be susceptible to DC coming in over the ground. 

 

  One of the reasons I got into all of this is because I had a Hum coming over my speakers.   I have a dedicated circuit for my amp and a separate dedicated circuit for the rest of my system.   I did and experiment where I turned off every breaker in my house except for the one connected to the amp.   Only the amp was connected to the speakers,  no interconnect.  When I plugged it in I had a hum.   When I put a cheater plug on it and lifted the ground, the hum went away. To my limited knowledge this led me to think I have TC coming in over the ground.  To my limited knowledge this led me to think I have DC coming in over the ground.   The manufacture of my CJ solid-state amp said that this was an invalid experiment.   However, I have lifted the ground in my amp.  I did that week where I added  (2) 2/0  cables from the chassis of my preamp and amp to the ground on my preamp. When I touch the cables from  The chassis of my amp to my preamp I get a loud hum.  I am in Denver in to clean everything up to see if I can fix this arm without the ground left and so I am able to connect the chassis. I am in deep. 

 

 

[drjimwillie]

The last lines above should read:

 I am endeavoring to clean up everything to see if I can fix this hum,  without the ground lift,  so I can connect The cables from the chassis of the amp to the preamp.  The cables from the chassis of the amp to the preamp 

Sorry for the typo. 

[Cornan]

Today my two ”ultimate LPSU” projects just took a big leap forward! ?

 

 

Now the 12VAC balanced isolated PS, the 15VAC balanced isolated ps and Sigma 11 discrete voltage regulator is behind my door step. Nothing but spare time can stop me now! ?

[John769]

Congrats!  Any sign of the 500va toroidal balanced isolation transformer?  

[Cornan]

Just now, John769 said:

Congrats!  Any sign of the 500va toroidal balanced isolation transformer?  

 

I have’nt got plans for a 500VA torodial balanced transformer at the moment, but the four 50VA transformers inside of those two balanced isolated ps are the same make as the 500VA transformer in their balanced isolation transformer and should therefore have the same sound signature that I promised to report back on. It will take a couple of weeks until I’ve put the first LPSU together though.

[John769]

Okay, thanks M.

[Abtr]

 

On ‎15‎-‎5‎-‎2018 at 4:33 PM, drjimwillie said:

@Abtr thank you so much for the extensive reply. 

 When you say wiring the transformer balanced eliminates common mode noise, is that because it does not get created in the first place or because it gets dumped into the ground,  or someplace else?

Reactive common mode noise from powersupplies will still be generated but with balanced power the noise in both legs of the PS is in opposite phase and cancels itself. This is called common mode noise rejection and it is comparable to the noise cancelation with balanced XLR connections.

 

Quote

I just posted two pictures of my transformer.   At the input there is a green wire going into the chassis.  On the output there are two gray wires coming out of the chassis.   No green wire.   How do I deal with this, please. 

At the input there are 2 green wires going from G into the chassis (yellow-green = savety ground, black-green = grounding to shield). At the output there is a yellow-green savety ground wire connected to G (ground) and to X4 (neutral) with a jumper. 

 

Quote

 If I plan to experiment with floating the secondary, balanced then I need to purchase and use the two pole GFI before I can experiment, correct? 

Yes.

 

Quote

 I plan to hardwire an Alt hifi DC blocker before the IT.  So then  I will only be susceptible to DC coming in over the ground. 

Correct. You can use a capacitor in the input savety ground wire (solid green) to block DC from ground (I use a 600V 18uF MKP type capacitor for that).

 

Quote

  One of the reasons I got into all of this is because I had a Hum coming over my speakers.   I have a dedicated circuit for my amp and a separate dedicated circuit for the rest of my system.   I did and experiment where I turned off every breaker in my house except for the one connected to the amp.   Only the amp was connected to the speakers,  no interconnect.  When I plugged it in I had a hum.   When I put a cheater plug on it and lifted the ground, the hum went away. To my limited knowledge this led me to think I have TC coming in over the ground.  To my limited knowledge this led me to think I have DC coming in over the ground.   The manufacture of my CJ solid-state amp said that this was an invalid experiment.   However, I have lifted the ground in my amp.  I did that week where I added  (2) 2/0  cables from the chassis of my preamp and amp to the ground on my preamp. When I touch the cables from  The chassis of my amp to my preamp I get a loud hum.  I am in Denver in to clean everything up to see if I can fix this arm without the ground left and so I am able to connect the chassis. I am in deep. 

 

 

 

On ‎15‎-‎5‎-‎2018 at 5:27 PM, drjimwillie said:

The last lines above should read:

 I am endeavoring to clean up everything to see if I can fix this hum,  without the ground lift,  so I can connect The cables from the chassis of the amp to the preamp.  The cables from the chassis of the amp to the preamp 

Sorry for the typo. 

DC offset in your AC power may saturate the transformer of your amp which might cause it to hum, but this is not the cause of hum through your speakers. Try the experiment with the input connections of the amp grounded (i.e., ground the outer connectors of the RCA inputs). Balanced power may reduce/elimininate hum from ground loops.

[Cornan]

Thanks for helping out @Abtr! Much appreciated! ??

[drjimwillie]

@Cornan will you please take a look at the  isolation mains transformer thread, I am trying to wire my transformer with star ground, but I don't think it's possible, I would like your input. 

also I would like to show off to you the power strip I built with Hubble 5362i industrial receptacles and Canare 4S11 star-quad cable.   I even used the star quad inside the metal box. It is based on the audience  AR6-PDC. 

 Maybe you can comment on the other mods I am thinking of, they look iffy  and I don't know if I should attempt it ?

[Cornan]

35 minutes ago, drjimwillie said:

@Cornan will you please take a look at the  isolation mains transformer thread, I am trying to wire my transformer with star ground, but I don't think it's possible, I would like your input. 

also I would like to show off to you the power strip I built with Hubble 5362i industrial receptacles and Canare 4S11 star-quad cable.   I even used the star quad inside the metal box. It is based on the audience  AR6-PDC. 

 Maybe you can comment on the other mods I am thinking of, they look iffy  and I don't know if I should attempt it ?

 

To wire a Topaz in a star-pattern might be tricky and not something I can help you to achieve. You should really follow the advice by @Abtr for the isolation transformer. He knows these things far better than I do. It does’nt matter if you want it floating or grounded. I personally prefer floating & balanced but as you know by now others disagree. It is really up to you to make that choice. All that is needed for a balanced floating IT is a 2-pole RCD/GFCI at the output towards your power distributor. I use a portable one from Brennenstruhl (but I am on 230VAC).

You want to wire the power distributor with a star-earth point because it ties all the grounds to a single point at the 2-pole RCD/GFCI.

 

Here is how my power distributor looks like:

 

 

Note the screw terminal blocks and how all ground wires are attached.

 

Here is how my balanced isolation transformer looks like:

 

 

Note the blue switch. With it I can ground or float the secondary in an instant. I never use the grounded secondary.

 

Remember that I got help from ATL Hi-Fi build these according to my wishes and requirements. He made sure they where properly done. 

 

Otherwise it it looks like you have thought of many great things that I know works a treat. With the isolation transformer I really recommend that you wire it balanced and listen with grounded secondary first. You do already hade dedicated mains as I have understood it. Even a grounded secondary is isolated. A floating secondary is just one step more isolated. You might not need it since your dedicated circuit. But you might need it! ?